The present invention relates to electronic parts formed in a multilayer structure by use of a resin or a compound material made by mixing powder functional material into this resin, and to a method of producing the same.
As a method of producing multilayer electronic parts by use of thin film conductors, JP-A-5-267063 discloses a method in FIG. 5 of the drawings attached herewith. As shown in the same, for instance, in case of producing an inductor, powders of raw material are mixed for providing desired functions as ferrite (Step S1), and granulating and pulverizing are carried out (Step S2). Then, the substances mixed and regulated in predetermined grain diameter are turned out to be enamels by use of binder and solvent (Step S3).
Laminating and baking steps carry out a screen printing (Step S4) of the ferrite paste, a pre-baking (Step S5) by rising temperature in a drying furnace, installation of inductor electrodes (Step S6) by forming the film through any of an evaporation, a spattering and an ion plating, and a screen printing (Step S7) of the ferrite paste. These steps are repeated several times until obtaining patterns of desired number. The forming of the electrode patterns is carried out simultaneously for many pieces of inductors.
Thereafter, products are cut per each of chips-(Step S8), and the chips are formed on sides with external electrodes by coating, evaporation or spattering (Step S9). Subsequently, other areas than the external electrodes are subjected to a silicone impregnation so that pores in the chip surface are impregnated with a synthetic (silicone) resin (Step S10). IF necessary, the external electrodes are subjected to an electroplating (Step S11).
For producing the multiplayer electronic parts using a resin or a compound material made by mixing functional materials (dielectric powder or magnetic powder) with this resin and thin film conductor formed by the evaporation or the like, the multilayer electronic parts are produced by repeating the printing of the compound material paste, the thermosetting and the forming of the thin film conductor.
In case of producing the electronic parts by the procedure of repeating the printing and the hardening as seen in the conventional examples, there have been problems that production cost is high, and a period till production is very long.
In addition, in the case of ceramics, for printing or forming the thin film conductor after baking, influences of fragility of a prime body are easy to appear, or as stress is loaded thereon, problems about cracks or warp easily occur. Laminated layers are baked for hours by nature, and when the number of layer increases, a long production time and cost are consumed.
Also in the case of the resin or the compound material, since the thermosetting and the printing are repeated to cause large stress loading thereon, the printed faces are roughened and when the number of layer increases, it becomes difficult to produce.
In view of the above mentioned problems, it is an object of the invention to provide electronic parts and a method of producing the same in which the producing time is shortened, and crack or warp are hard to occur, reduction of cost can be attained, and the production can be performed even if the number of layer is many.
A method of producing electronic parts of a first aspect of the invention is characterized by comprising: forming a resin or a compound material made by mixing powder-like functional materials with this resin into thin plate, hardening it to be core substrates; forming thin film conductor on at least any of front and back surfaces of the core substrate through any of an evaporation process, an ion plating process, an ion beam process, a vapor deposition process, and a sputtering process, followed by patterning; forming the resin or the compound material made by mixing powder-like functional materials with this resin into the prepregs like thin plates, alternately laminating half-hardened prepregs and the core substrates, and subsequently hot-pressing and unifying into multilayer parts.
As seeing, if the core substrate and the prepreg are separately produced, and lamination and hardening are carried out concurrently, the production time can be shortened and the cost is lowered. Since the whole is once hardened by hot-pressing, crack or warp are hard to occur, and the production is possible even though the number of layer is many.
Further, the thin film conductor can be made thin, so that it is possible to firstly make parts thin (in particular, this effect is remarkably in a capacitor), secondly heighten patterning precision and accuracy in layer-to-layer, and thirdly avoid migration because the thin film conductor is thin so that the resin is buried around its periphery. In this application, the term xe2x80x9cpowder-likexe2x80x9d includes grain form, flake form, needle form, spike form, or the like.
An electronic part of a second aspect of the invention is characterized by comprising: a core substrate made by forming the resin or the compound material made by mixing the powder functional materials with this resin into thin plates, and hardening it; a thin film conductor formed on at least any of front and back surfaces of the core substrate through the film forming technique and carried out with the patterning; and an adhesive layer formed with the resin or the compound material made by mixing the powder-like functional material with this resin, and interposed among core substrates formed with the thin film conductors; wherein laminated layers made of the core substrates and the prepregs for the adhesive layers are unified by hot-pressing.
If the electronic parts are composed of such a laminated structure, as mentioned in the first aspect, the production time can be shortened, the cost is lowered and crack or warp are avoided from occurrence.
The electronic part of a third aspect of the invention is, in the second aspect, that the thin film conductor has thickness less than 5 xcexcm.
When the thickness is more than 5 xcexcm, time is taken too much for forming the thin film, and it is difficult to shorten the production time. Because the thickness restricted less than 5 xcexcm, it is possible to avoid the manufacturing time from becoming long. In case of the thickness is less than 1 xcexcm, a conductor resistance becomes large. Therefore, in order to maintain a Q value at a predetermined level, thickness of the thin film conductor preferably has more than 1 xcexcm. However, in case of capacitor or noise removing circuit which allows large loss, thickness of the thin film conductor may be less than 1 xcexcm, but more than 0.3 xcexcm.
Moreover, according to the electronic part of the present invention, as a resin, at least one thermosetting resin selected from a group consisting of epoxy resin, phenol resin, unsaturated polyester resin, vinyl ester resin, polyimide resin, bismaleimidotriazine (cyanate ester) resin, polyphenylene ether (oxide) resin, fumarate resin, polybutadiene resin, and vinylbenzyl resin, or at least one thermoplastic resin selected from a group consisting of aromatic polyester resin, polyphenylene sulfide resin, polyethylene terephtalate resin, polybutylene terephtalate resin, polyethylene sulfide resin, polyethl ether ketone resin, polytetrafluoroethylene resin, polyarylate resin and graft resin, or a composite resin composed of at least one of the thermosetting resin and at least one of the thermoplastic resin may be used.
Moreover, according to the electronic part of the present invention, as the powder-like functional material, at least one ferrite magnetic material selected from a group consisting of Mnxe2x80x94Mgxe2x80x94Zn based magnetic material, Nixe2x80x94Zn based magnetic material, and Mnxe2x80x94Zn based magnetic material, or at least one ferromagnetic metallic magnetic material selected from a group consisting of carbonyl iron, iron-silicon based alloy, iron-aluminum-silicon based alloy, iron-nickel based alloy, and amorphous (iron based or cobalt based) alloy, or at least one dielectric material selected from a group consisting of BaOxe2x80x94TiO2xe2x80x94Nd2O3 based dielectric material, BaOxe2x80x94TiO2xe2x80x94SnO2 based dielectric material, PbOxe2x80x94CaO based dielectric material, TiO2 based dielectric material, BaTiO3 based dielectric material, PbTiO3 based dielectric material, SrTiO3 based dielectric material, CaTiO3 dielectric material, Al2O3 based dielectric material, BiTiO4 based dielectric material, MgTiO3 based dielectric material, (Ba, Sr)TiO3 based dielectric material, Ba(Ti, Zr)O3 based dielectric material, BaTiO3xe2x80x94SiO2 based dielectric material, BaOxe2x80x94SiO2 based dielectric material, CaWO4 based dielectric material, Ba (Mg, Nb)O3 based dielectric material, Ba (Mg, Ta)O3 based dielectric material, Ba(Co, Mg, Nb)O3 based dielectric material, Ba(Co, Mg, Ta)O3 based dielectric material, Mg2SiO4 based dielectric material, ZnTiO3 based dielectric material, SrZrO3 based dielectric material, ZrTiO4 based dielectric material, (Zr, Sn)TiO4based dielectric material, BaOxe2x80x94TiO2xe2x80x94Sm2O3 based dielectric material, PbOxe2x80x94BaOxe2x80x94Nd2O3xe2x80x94TiO2 based dielectric material, (Bi2O3, PbO)xe2x80x94BaOxe2x80x94TiO2 based dielectric material, La2Ti2O7 based dielectric material, Nd2Ti2O7 based dielectric material, (Li, Sm)TiO3 based dielectric material, Ba(Zn, Ta)O3 based dielectric material, Ba(Zn, Nb)O3 based dielectric material and Sr(Zn, Nb)O3based dielectric material, or composite functional material composed of at least two of the above mentioned ferrite magnetic materials, ferromagnetic metallic magnetic materials, and dielectric materials may be used.